Brake actuating mechanism



y 2, 1959 BE. HOUSE 2,886,141

BRAKE ACTUATING MECHANISM Filed Jan. 4, 1955 2 Sheets-Sheet, 1

INVENTORY BRYAN E. Hausa ATTORNEYS 2 Sheets-Sheet 2 Filed Jan. 4, 1955INVENTOR BRYAN [5. HOUSE BY M9W/ ATTORNEYS Un d States a n d e 2,886,141BRAKE ACTUATING MECHANISM Bryan E. H ouse,-Ashtabula, Ohio, assignor toRockwell- .Standard Corporation, a corporation of Pennsylvania Appliation Jannary 4, 1955, Serial No; 419,714 he 4 Claims. Cl. 188-78)invention relates to improvements in vehicle. brakes and hasrparticularreference to brake cam actuators.

Brakes with hydraulic cylinder actuators which apply f equal actuatingforce directly to both brake shoes orrwith floating head'actuators whichbalance the actuating force applied directly to both brake shoesgenerally wear one, shoe lining more quickly. than the other as arresultof the self-energizing eflort of a conventional fixed-anchor hrakeshroev This self-energizing effort of a conventional fixed-anchor axisbrake shoe results from a wrapping gup or self-applying action createdby the rotatlng brake drum attempting to rotate the brake shoe towardits anchor pin, This creates pressure between the brake drum and thebrake shoe in, addition to that transmitted to the brakeshoe by the:actuatonf When the brake, drum at-.

tempts to rotate the shoea-way from its anchor pin, there etfort oftheshoe results from the force supplied by the .30 is no suchwrappingaction and the only effective braking force to one brake shoe asit does to the other brake t A further object is to provide in novelcombination a crank member and a freely pivoted brake shoe actuaton,Another object resides in the provision. of a novel brake shoe actuatingcam having opposed sockets which pivotally receive brake shoe actuatingpush rods.

A further object is a novel disc cam construction com prisinga body withend plates which restrain brake shoe actuating push rods in position inrespective internal cam recesses in the body.

Another object resides in improved interchangeable shoe actuating pushrods having brake shoe embracing portions at one end.

Additional objects and advantages of the invention will become apparentfrom the following description in cone junction with the accompanyingdrawings and the appended r claims.

The drawings illustrate a suitable mechanical embodi- 20 ment forpurposeso-f disclosing the invention, are :for pur- ..-poses.ofillustration only and are not to be taken in 1a limitedor restrictivesense, as it will be apparent to those skilled in the art that variouschanges in the illustrated.

embodiment may be resorted to without in any way exceeding the scope ofthe invention.

In the. drawings: r t Figured is a side elevational view of a brakeassembly according to the preferred embodiment of the invention; I

Figure 2 is a partial sectioned view of the brake assemblyl alo ng line22 of Figure 1, which illustrates actu q i ator and I anchor details;

actuator. Inthis type of brake one or the other of the f rotation,willjhave a self-energizing factor and,if primary This vvonld require adiflerential inthe actuating forces applied tofthe two brake shoes.

vention, increased braking effort is thehpr imary object, 1 thedifferential inactuating forces can be so arranged that a greater "thanconventional -relative actuating force is applied to .the shoe normallysubject to the self-energizing faeftor hand increased dvantage istakenof. the self: eneij izing force: for increasing the braking actionsIn the preferned embodiment of the invention herein disclosed theactuating lforce transmitted to the shoe normally subject toaself-eiiergizing factor from primary druin rotation 1s approximatelyitwice that transmitted the other shoe further object of this inventionis to provide an irnproved vehicle brake actuator and brake assembly inwhich the actu ator applies moreactuatingforce to the vehicleforwardmovement than to the other brake shoe.

further bjectof. the invention is to! provide a novel;

11f, however, as in thepreferred embodiment of the in -".1

.It is the.primaryfobjectofthis invention to provide a brake mechanismemployinga novel mechauicallysirn ple and inexpensive shoe actuatingmechanism. for obtaini-n'goptimurn brakingfpressures. A

tends from opening 46 in one ishoe web. to the correspondinglopening 46the other shoe web, returns the shoes 32 to non-braking position inabutment with the brake shoe subject to a self-energization factorduring 16 brake shoejactuator.mecha11ism wherein a cam operative 1yconnected at spaced opposed points to the braheshoes Another objectresides in the provision of afloating is freely jo rnalled on anoperating eccentric.

brake actuator, which utilizes a dynamically balanced force conple toapply unequal yet predeterminedly proportioned aetuating" forces totherespective brahe shoes: e e herobject is to provide a floating camactuator which tr 7 50 prevents loss A ofhgrease from the support.

member 14 is formed with an integral hub 64 where it ansmitsapproximatelytwice as much actuating a through enlarged openings 38 inthe Figure 3 is a sideydetail view of a push rod; and

Figures 4 and 5 illustrate disccamdetails. r 1

Referring now to the drawings and more particularly to Figure 1, theillustrated brake assembly10 is gener- :ally conventional except for theimproved flat disc cam actuator unit 12, the crank member 14, the cranksupport 16 mounted on backing plate 18, and the push rods 20interconnecting the cam actuator unit with the ends of the brake shoes.

A conventional brake backing plate 18, which also serves as a dustshield for drum 30, is mounted on fixed flange 22 or axle 24 as byrivets at 26. Adjustable eccen tric anchor pin assemblies 28, which maybe the same i as those disclosed in United States Letters Patent No.

-2,435,955 to L. R. Buckendale et al., provide initial and wearadjustment for brake shoes 32 Which are pivoted thereonat one end.Eccentric cams 34 which are conyentional are rotatable for secondarybrake shoe adjustments. Guide pin assemblies 36,

49, help maintain shoe alignment. .Resiliently spring hlased guide pins44 also extend through enlarged openings 46 in the shoe Webs and provideadditional support for shoe alignment Shoe return spring 48, whichexrespectivecarns 34 when the actuating force transmitted through thecam actuator 12 is relaxed.

rotatably mounted at 52 upon the inboard end shaft 53 of crank member14; A bolt 54 carried by lever 50 cooperates with a groove 56 in shaft53 to lock lever 50 M e e e e 14. Crank support 16 1s rlgidly mounted.on backing plate 18 as by welding.

axially in position on crank member Grease may be introduced through afixture in threaded opening in the side of support 16 for lubricatingthe bearingsection 60 of shaft 53. An oil seal 62 retained inthe end ofsupport in abutting relationwith lever Crank Patented May 12,1959.

which extend freely respective shoe webs An actuating lever 50 issplinedor otherwise non-.

and the'cam body being permanently fastened together into a unit by anyconvenient means such as riveting or spot welding at 75. The camactuator is provided with an eccentric bearing opening 76 passingthrough both the end plates 74 and cam body 72, and it is journalledfreely thereby on crank pin 70 (Figures 1 and 2). Cen-' tral cam body 72is provided with two recesses 78 and 80 on opposite sides of adia'metral line throughthe eccentric opening 76. The bottom of eachrecess 78 and 80 is curved and provides a pivot seat for the similarlyrounded end 82 of a flat sided actuator rod 20. The bottom of eachrecess and the center of opening 76 are substantially diametricallyaligned, with the bottom of recess-78 located approximately midwaybetween opening 76 and the bottom of recess 80, as illustrated in Figure4.

Cam body recesses 78 and 80 in conjunction with the two end plates 74provide sockets in the periphery of the cam actuator unit 12, the socketforming portions of end plates 74 serving as socket side walls whicheffectively retain and prevent lateral rocking of the actuator rods 20.To positively prevent operative displacement of the rod from recess 80,which is closest to the peripheral marginof the disc actuator, opposedinwardly extending depressions 83 are provided in end plates 74, andeifectively increase the side wall length of recess 80 (Figure 5 The twobrake shoes 32 are identical and are pivoted at adjacent ends by theaforementioned adjustable anchor pin assemblies 28. The other ends ofthe shoes 32 have curved bottom edge notches 84 provided in the shoewebs 40 to pivotally receive the outer curved ends 85 of actuator rods20. As illustrated in Figure 3, the end 85. of

each actuator rod has rectangular tongue members I '40 86 spot welded at87 on each side of the rod with converging extensions 88 that bracketthe sides of the shoe web 40 with a snug sliding fit.

Actuator rod tongue extensions 88 extend as a fork beyond the shoenotches 84 on each side of shoe webs 40 and maintain aligrnnent andaxial position of the floating actuator assembly 12 on the crank pin 70by the cooperation of ends 82 within the recesses 78 and 80 upward wouldactuate the brake when pulled counterclockwise.

In operation 'when lever 50 is pulled counterclockwise,

as seen in Figure l, the eccentric crank pin 70 moves counterclockwisein a circular are about the centerof crank shaft 53. As the bearingopening 76 of disc cam actuator 12 is so moved counterclockwise by pin70, the bases of recesses 78 and 80 exert differential forces on theends 82 of the respective push rods 20, to transmit difierent forcesthrough the rods 20 to urge the brake shoes. 32 toward the drum. This iseffectively a force couplev and, since the summation of forces aboutopening 76 or either abutment point of push rods 20 with disc cam 12must equal zero, it is a dynamically balanced force couple. V I

In effect the crank 14 provides an operating eccentric and the actuatorunit is a lever freely pivoted upon the eccentric pin 70, fulcrumed uponthe rear brake shoe at socket 80 and applying the primary braking forcetothe' forward or leading brake shoe (bottom shoe in Figure actuatorrecess 78 faces the shoe subject to a self-en-- 1). This primary brakingforce coupled with the ntendant self-energization produced when thebrakes are applied with the drum rotating counterclockwise in Figure 1,provides a very substantial braking force between the leading shoe andthe drum.

Actually the force exerted at recess 78, on a push rod 20, times thedistance OA along center line X--X from the center of opening 76 equalsthe force exerted at recess 80, on a push rod 20, times the distance OBalong center line X--X from the center of opening 76. The distance O-Ais equal to one half the distance OB so that the force at recess 78 is Itwice the force at recess 80. It is also true that the force exerted bypin 70 against a side of opening 76 plus the force at recess 80 againsta push rod 20 equals the force at recess 78 against the other push rod20. The floating arrangement of disc cam actuator 12 about pin 70 helpsmaintain actuator alignment and axial position and permits the actuator12 to assume and maintain a dynamically balanced state whenever thelever 50 is operate for brake actuation.

In the embodiment of Figure l the disc cam actuator 12 is so assembledon crank member 14 so that the center ergizing factor during the primarydirection of brake drum rotation.

The actuating lforce transmitted to left hand shoe 32 of Figure 1 may bemade smaller than that transmitted to" the right hand shoe 32 to obtainmore equalized braking j pressures, by reversingthe actuator 12 so theactuator" recess 80 actuates the left hand brake shoe 32[ The" brakeshoes which are identical may be reversed'after 'a period of operationto obtain full lining wear on each 'shoe.

Rods 20 are identical and interchangeable in the assembly.

From the foregoing it is apparent that there is hereby provided animproved vehicle brake assembly having a novel cam actuator unit andmode of operation.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated'by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency ofthe'claims are therefore intended to be embraced therein.

What is to be claimed and desired to be secured by United States LettersPatent is: i

1. In a brake having a pair of brake shoe assemblies pivoted upon meansfor urging said brake shoe assemblies toward each other, an actuatorassembly operatively connected between the other ends of saidshoeassemblies comprising a crank arm rotatably mounted upon 'a fixed axison said support, a crank pin on said arm paralwalls of said sockets forconfined movement in a path transverse to the axis of said bore and onthe adjacent ends of the brake shoe assemblies; and means onthe ends ofsaid rods embracing and engaging said brake shoe assemblies and, withsaid rods and cam member sockets, axially maintaining said cam inposition on said crank arm.

2. In a braket assembly for a highway vehicleof th on a fixed axis; acrank rigid with said shaft providing a crank pin eccentric with respectto the shaft axis; a disc shaped lever member having an eccentric borewhereby said lever member is freely pivoted on said pin, said dischaving two recessed oppositely disposed peripheral edge socketsproviding deep seats with spaced apart essentially parallel side wallstransverse to the axis of said bore, the bottoms of the seats of saidsockets being differently spaced in the same direction from said boreand seat bottoms lying substantially on a disc diameter passing throughthe center of said bore; a first push rod rockably disposed in andfitting said side walls of one of said sockets of said lever member forconfined movement in a path transverse to the axis of said bore, andembracing and rockably engaging said other end of the brake shoe whichis subject to self-energization during forward movement of said vehicle;and a second push rod rockably disposed in and fitting said side wallsof the other of said sockets on the opposite side of said lever member,which is at a greater distance from said crank pin than said first pushrod, for confined movement in a path transverse to the axis of said boreand embracing and rockably engaging said other brake shoe, so that whensaid shaft is rotated to operatively expand the shoes toward the drumthe lever is effectively fulcrumed on said second push rod and exerts anappreciably greater brake actuating force upon said shoe that isnormally subject to self-energization.

3. A brake shoe actuator disc having an eccentric transverse throughbore whereby said disc is adapted to be freely pivotally mounted on abrake actuator crank pin, said disc having two recessed oppositelydisposed peripheral edge sockets providing deep seats with spaced apartessentially parallel side walls transverse to the axis of said bore,adapted to rockably engage the ends, and confine the rocking, of pushrods extending from adjacent brake shoe ends to a path transverse of theaxis of said bore, said sockets being differently spaced in the samedirection from said bore and the bottoms of said seats lyingsubstantially on a disc diameter passing through the center of saidbore.

4. A brake shoe actuator disc as defined in claim 3, wherein said discis an integral sandwich construction comprising a solid flat cam bodycore of essentially circular outline with an eccentric transverseaperture and two round bottom cutouts on opposite side edges of adiametral line of the core through said aperture, the bottoms of saidcutouts being essentially on said diametral line; and a disc shapedplate disposed and rigidly secured on each side of said core, each discshaped plate having an eccentric transverse aperture aligned with saidcore aperture, said cutouts and the overlying portions of said sideplates constituting said deep seat sockets.

References Cited in the file of this patent UNITED STATES PATENTS1,753,208 La Brie Apr. 8, 1930 1,762,691 La Brie June 10, 1930 1,846,124La Brie Feb. 23, 1932 1,862,309 House June 7, 1932 1,964,163 La BrieJune 26, 1934 2,106,167 Colman Jan. 25, 1938 2,134,512 Hall Oct. 25,1938 FOREIGN PATENTS 283,375 Great Britain Jan. 12, 1928 1,002,462France Oct. 31, 1951 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 2,886,141 May 12, 1959 Bryan E. House s in the-printed specification n It is hereby certified that error appear tionand that the said Letters of the above numbered patent requiring correcPatent should read as corrected below.

Column 1-, line 23, for "ehroe" read shoe for "brake't" read brake"column A, line 70,

,Signed and sealed this 8th day of September 1959.

Attest:

ROBERT C. WATSON KARL H. AXLINE Attesting Officer I Commissioner ofPatents

